Plants come in varieties that are either cultivated or grow wild. Cultivated plants are planted by colonists in a growing zone or a hydroponics basin, mainly for food. Wild plants grow naturally throughout the map. Some wild plants spread themselves via seeds. Animals mostly graze on wild plants but will happily eat cultivated crops as well, including tamed animals. Since Alpha 17, they leave ash on the ground when burnt.

Growth Rate Factors

Fertility

The medium used to grow the plants in matters for both for growth speed and if growing a plant is even possible in any given spot.

Most plants have a Fertiltiy requirement of at least 50%. However, most Trees come out with a measily 30% Fertility.

Most plants have a <fertilityFactorGrowthRate>, which is used to determine how "picky" a plant is about how fertile its terrain needs to be. Ingame this is also denoted as "Fertility sensitivity". A plant with a <fertilityFactorGrowthRate> of 0 will not care if it is planted on fertile soil or sand; it will grow at the same rate on any terrain tile that will accept its roots. In contrast, a plant with a <fertilityFactorGrowthRate> of 1 will not grow so well if it is planted on anything less fertile than standard soil.

Note: Beyond 100% Fertility, high Fertiltiy Sensitivity becomes a bonus rather then a penalty. For such cases highly sensitive plants are preferable.

Temperature

For normal growth rate, plants require temperature between 10 °C (50 °F) and 42 °C (107.6 °F). Plant growth rate drops by 10.0% for each degree Celsius below 10 °C (50 °F), and by 6.25% for each degree above 42 °C (107.6 °F). The plant's info window will show 'Out of ideal temperature range (growing at xx% of normal speed)'. Plants will not grow when the temperature falls below 1 °C (33.8 °F) or rises above 57 °C (134.6 °F). The plant's info window will show 'Out of ideal temperature range (not growing)'. If the temperature drops below -10 °C (14 °F), it will either die or lose its leaves, depending on the type of plant. Leafless plants cannot grow, and will take a full day to regrow their leaves after the temperature rises back above -2 °C (28.4 °F).

Light

This minimum light value can be modified by changing a plant's <growMinGlow> value. When a plant lacks adequate light its info window indicates this with the text 'Needs light level: ##%'. Over that minimum a plant's growth rate will increase until it reaches its optimal light level (100% standard). A plant's optimal light level can be modified by changing its <growOptimalGlow> value.

Most artificial light sources only provide 50% light. Only decorative plants can grown under such poor light conditions. The sun lamp provides 100% light in its radius, and is thus usually required for any indoor growing.

Rest

All plants rest from hour 19 through hour 5. More accurately, plants rest for 11h of the day, leaving 13h of the day for growing.

During the plant resting time period, plants will not grow no matter the light level.

A new constant, Growing Ticks/Day, can be found by multiplying Ticks/Day by 13/24 (approx. 54.167%) :

Growing Ticks/Day = (60,000 Ticks/Day × 13/24) = 32,500 Ticks

Instant Growth

All plants receive an instantaneous growth of 5% when sown/planted.
This is relevant because it means that all plants only need to grow 95% from the moment they are planted to become fully grown (100%).
You'll see this show up in a later equation as a new value: Growth Remaining
You can use this value to help determine how long a plant has left before it is fully grown.

Actual Growth Time

The Growth Time displayed in-game can tend to confuse a player into thinking a plant will be fully grown in X number of days.
Due to the various Growth Rate Factors (Fertility, Temperature, Light) and every plant's need to rest, the growDays or "Growth Time" listed in-game is not an accurate/intuitive representation of how long a plant actually takes to grow.
For example: A Raspberry Bush (3:growDays), on Soil (1:Fert), experiencing optimal temperature and light 100% of the time (1:Temp, 1:Light), will take approximately 5.18 actual in-game days to grow.
It is important to remember this when setting up your growing zones.

Lifespan

Even if they are not harvested or eaten, plants do not live forever. The counting of their lifetime starts when the plant is sown/spawned. Since plants only grow during certain hours, and growth rate varies greatly under different circumstances, it is possible for a plant to die before it reaches full maturity or even while still on the initial progress. This is called "dying of rot".

The lifespan of a plant is calculated by simply multiplying the plant's growDays by its lifespanFraction.
Most vanilla plants have a default lifespanFraction of 5, but some go as high as 8. Trees do have this property as well, but due to their long growth time this is rarely relevant

Plant Growth approaches

The player has a number of options to get plants grown for food and raw material. Each of them has their up- and downsides and a proper mix of them is nesseary to be resistant to disruptions, inclding seasons.

Fields

You just define a growing zone, select the crop and let nature and your pawns set to growing do the rest.

Upsides:

No cost, excluding the work time to clear, sow and harvest. Nearby trees that could shade your crops will be cut down as well

Available at the start, regardless of technology level

All crops can be planted in ground

Downsides:

Not all tiles can be planted

In ground growing is dependent on the soil fertility for that tile

Outdoor growing is dependent on the local seasonal weather and even impossible in the coldest biomes

Highly vulnerable to irregular temperature variations such as cold snaps and heat waves that could stop growth or even kill plants

Full resistance to temperature variations once heaters and coolers are built

Slightly increased growth, due to the persistent 100% lighting level from the sun lamp during the day

Energy shortfalls will not directly kill existing plants, only if the temperature becomes too high or too low

Immune to events like toxic fallout and volcanic winter

Downsides:

Requires fertile soil. Not all tiles can be planted including those under mountain roofing

Needs tiles that can support building walls to support the roof, which is difficult in swamp biomes

Sun lamps require incredible amounts of power during the day: 1-2 solar generators worth of production for the entirety of the plant's non-rest cycle

Energy production to power sun lamps can cost incredible amounts of resources, both upfront and in maintenance/refueling

Sun lamps are sensitive to power outages, which usually won't kill in ground greenhouse crops unless the temperature dips low enough outside to affect plants inside

May require research to unlock

Hydroponics Bay

Hydroponics is the knowledge of growing plants without soil, using a nutrients dissolved in a water bath. In game it requires research to unlock and the building of one or more Hydroponics basins. These basins will override any growing zone they are placed on top of.